Long-term nitrogen deposition alters the soil bacterial community structure but has little effect on fungal communities

Subtropical Moso bamboo (Phyllostachys edulis) forests have become hot spots for nitrogen (N) deposition in China. However, the effect of long-term N deposition on the structure of soil microbial communities in different horizons of these forests remains unclear. To investigate the influence of extended N deposition on soil bacteria and fungi, a simulated N deposition field study was conducted in Fujian Province with four N deposition levels (0, 20, 40 and 80 kg N hm−2 a−1). The absolute abundances, diversity, community structure, and potential functions of soil bacteria and fungi were investigated after 10 years of simulated N deposition. The results indicated that there was no significant effect of N deposition on the abundance or diversity of soil microbes in either the organic or mineral horizons of Moso bamboo forests. However, under rates of 40 and 80 kg N hm−2 a−1, long-term N deposition altered the structure of the soil bacterial community in the organic horizon. Specifically, there was a 27.75∼36.40 % increase in the relative abundance of Actinobacteria, while that of Acidobacteria decreased by 24.40∼27.52 %. Redundancy analysis (RDA) demonstrated that soil total carbon (TC) was the key variable influencing the bacterial community structure in the organic horizon. Analysis of potential microbial functions showed that in the organic horizon, the rates of chemoheterotrophy significantly decreased under 80 kg N hm−2 a−1. However, N deposition did not noticeably impact the fungal community structure in either soil horizon. Our study suggested that under 10 years of N deposition, only the bacterial community composition and function in the organic horizon was affected, indicating that soil bacteria are more sensitive to N deposition than fungi in subtropical Moso bamboo forests. Therefore, further research is necessary to fully understand the impact of N deposition on fungal community composition in the soil organic horizon and on the microbial community in the mineral horizon of subtropical bamboo forests. This study provides valuable insights for informing future environmental management and conservation strategies.